Understanding the recognition and signaling events that allow a plant to successfully combat infection is a high priority in plant research, and can contribute to reducing the vulnerability of plants to disease and resulting economic loss, and use of pesticides. This proposal describes a biochemical approach to elucidate the mechanism by which one resistance protein (N) is able to recognize and combat infection of the tobacco mosaic virus (TMV). Increasing evidence for several R genes has indicated that they often function not by recognizing the pathogen directly, but by recognizing specific cellular modifications elicited by the pathogen. The mechanism by which N is able to recognize the presence of TMV is not clear. This proposal aims to characterize this mechanism by identifying 1) N-interacting proteins and 2) TMV-interacting factors in the cell. Interacting proteins are likely to include downstream signaling components of disease resistance pathways as well as cellular targets of TMV action in the cell. Knowledge of this mechanism will not only benefit defense against TMV, but also potentially many other diseases, since both resistance genes themselves and the signaling pathways they induce are highly conserved across plant species. [unreadable] [unreadable]